Radiation can help or harm — and sometimes do both at the same time. When used as a medical treatment, radiation kills cancer cells. But any nearby healthy cells hit by the radiation also will die or suffer lasting harm. Unless, that is, the body quickly repairs them.

Scientists have identified a chemical that might help with these repairs. It’s called DIM, and it develops in the body after eating a diet rich in broccoli and related vegetables, such as cauliflower, Brussels sprouts and kale.